People with genetic vulnerability for adult depression are more likely to have emotional and social problems in childhood, including symptoms of attention deficit hyperactivity disorder (ADHD), according to a study published in the journal JAMA.
The international team, from working groups of the Psychiatric Genomics Consortium, found the same link with genetic scores related to insomnia, neuroticism and body mass index.
Conversely, higher scores for educational achievement and emotional wellbeing were related to less childhood problems, and this link became stronger with age, suggesting the effects of genetic variants really kick in around the teens.
On their own, genes only have very small effects on traits, but it’s now understood that psychiatric disorders are highly polygenic – influenced by numerous genetic variants – enabling scientists to link groups of genes to health problems.
This study was prompted by a quest to understand why childhood problems often persist and evolve into adult mood disorders – major depression and bipolar disorder.
“About 50% of children and adolescents with psychiatric problems continue to have mental disorders in adulthood,” says senior author Professor Christel Middeldorp, from the University of Queensland, Australia.
“They are also more likely to have reduced educational attainment, increased BMI and increased insomnia in adulthood. We were interested in investigating whether genetics play a role in these observed relationships.”
The researchers analysed nearly 30 years of genetic data collected up to 2002 from around 43,000 children and teenagers from seven population cohorts across Europe.
They used genetic risk scores comprised of a person’s vulnerability to developing a trait or disorder based on differences in their DNA.
“We calculated a person’s level of genetic vulnerability by adding up the number of risk genes they had for a specific disorder or trait,” Middeldorp explains, “and then made adjustments based on the level of importance of each gene.”
They were somewhat surprised to find that bipolar disorder did not show the same associations as adult depression, given its genetic link with ADHD, depression and other “behavioural-cognitive phenotypes” such as educational achievement and wellbeing.
Confirming that genetic variants partly explain the link between childhood and adult traits could move us towards more targeted attention and treatment for at-risk individuals, says first author Wonuola Akingbuwa from the Vrije Universiteit, Amsterdam – but we’re not there yet.
“Although currently genetic risk scores are not accurate enough to make individual predictions for people,” she says, “they may become, in the future, in combination with other risk factors.”
These include multiple socio-emotional influences that can fuel the continuity of mental health problems throughout life, which Middeldorp says should ideally be investigated in conjunction with genetic factors.
Natalie Parletta is a freelance science writer based in Adelaide and an adjunct senior research fellow with the University of South Australia.
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